Human
Humans consist of the "normal" people who are not Grimms, Wesen, or Non-Wesen beings. Kehrseite is the Wesen word for a "normal" human (KERR-zy-tuh; Ger. "reverse side"). A Kehrseite who knows the truth about Wesen is known as a Kehrseite-Schlich-Kennen (SHLISH-kih-nihn; Ger. schlich "sneaked" + kennen "to know, be aware of"). According to Monroe, the only reason why Kehrseite are capable of accepting or believing in the inexplicable is because they can visualize or conceptualize it from their own perspective, not because of them actually seeing it for themselves. On the other hand, he has acknowledged that many people are hospitalized at mental institutions because they have "spent their lives trying to wrap their minds around things they've seen and can't explain." He has also said that the vast majority of humans are not able to transition from a Kehrseite to a Kehrseite-Schlich-Kennen because they just can't process seeing Wesen right in front of them, akin to looking "directly into the boiling core of the raw universe." Under rare or unusual circumstances, it is possible for humans to be turned into Hexenbiests; it is not known if it is possible for humans to be turned into other Wesen, though it may be possible to alter a human's DNA in utero similar to how Dr. Higgins changed the DNA of her son. Juliette Silverton, after inhaling a Verfluchte Zwillingsschwester potion in order to turn into Adalind Schade, slept with Nick while she was still in the form of Adalind to help him get his Grimm powers back. However, as a side effect, she gradually turned into a Hexenbiest. Humans that turn into Hexenbiests are even deadlier than naturally born Hexenbiests. It is also possible for humans to gain the attributes of a particular Wesen through a practice typically performed by Santeria priests, who are often Vibora Doradas. Vibora Doradas use their fangs to inject paralyzing venom into their Wesen victims, which keeps them woged while the Vibora Doradas flay the skin off their face. They use the skin to make masks, imbuing them with the ability to transfer the traits of the particular Wesen they originated from onto an owner when they put the masks on. However, a contract must be signed in blood, and the masks must "accept" its owner at first, and if a human wears this type of a mask too often, it will drive them to insanity and eventually graft itself onto the skin of its wearer, only removable at that point through the Ceremonia de Desgracia (Span. "Ceremony of Disgrace"). When it comes to Wesen diseases, there are very few, if any, diseases that have been shown to affect humans in a way that causes a transformation. One such disease, however, is Lycanthropia, though the instances of it affecting a human have been very rarely documented, if at all. As with Wu, however, the disease does gradually manifest in humans, albeit a bit differently than how it affects Blutbaden. If a human is scratched or bitten by a Lycanthrope, one will first develop several symptoms, including night sweats, blurry vision, headaches, and body aches or sharp muscle spasms. Eventually, the disease will progress to the point where a primal side emerges when in a heightened emotional state that physically manifests in the form of a Neanderthal-like creature. No cure is currently known. If a human and a Wesen have offspring together, then a hybrid like Sean Renard will result. There has also been one documented case where multiple Wesen body parts were able to be successfully transplanted to a human body, one that was not living, and revive the resulting hybrid creature. However, this creature was extremely violent and viewed itself as a monster, becoming vengeful over the rejection of what it had been made into. Eventually, there were few options left other than to kill it. It is not known if this violent behavior would occur if human body parts were transplanted to a Wesen species.